Digital Photography

http://www.brighthub.com/multimedia/photography/articles/68626.aspx

There first tip is when the person is standing have them stand at a slight angle to the camera, and their head facing the camera so the body looks slimmer, and it looks like a more natural pose. If the person is sitting have them resting against something or have them lean forward on their knees otherwise they will look tense. Sitting with their legs crossed or straight out in front of them makes them look awkward as well. Shoot the picture from the side to avoid unusual body proportions that make the legs look closer than the face is. A good pose is laying down. The person can prop their head up by placing their fists under their chin while laying on their stomach. Or they can prop up their body with an elbow while laying on their side.

http://www.digital-slr-photography-tips.com/portrait-poses.html

This site says that these are the most important things to concentrate on while taking portraits of people-
-eyes are the most important.
-the subjects comfort.
-shoulder placement.
-head position/tilt.
-Hands and arms.
-Mouth and lips.
-Feet and legs.
The eyes are important because they are very expressive and you want to capture the intensity and emotion in them. The best way to capture the activity and intensity in the eyes of your subject is to start a conversation with them.

Head and shoulder placement is important because if the camera is pointed directly at the person, the resulting pose becomes static and the subject looks wide. The shoulders and head should be 45degrees away from the cameras. Doing this slims down the subject and creates a nice visual interest. It is best to tilt the subjects head, because when tilted, you create a line of interest from the person’s eyes that draws the viewer’s interest.

Mouth and lips may be more expressive than the eyes. Take many types of shots, including smiling, serious, laughing, etc. by complimenting your models you can get natural smiles. It is far better to do this than getting a forced smile. Remember to ask your model to moisten their lips every once in a while. Moistened lips catch light and sparkle.

Arms and hands. Arms that are directly to the side will cause bulk which is something to avoid. Having your model hold their arms out slightly will create a foundation for your composition that directs your viewer up to the models face. Female models hands should be posed gracefully either with a slight bend in the wrist or just the outer edge of the hand. For men, you want to create a masculine, strong, showing with the hands by holding something like a cup of a pencil. This creates a bit of a bulk look that subtly showcases strength. Alternatively, you can have your male model cross his arms across his chest. If you photograph feet directly, they will look unattractive. Its best to have your model put their weight on the back foot with a slight bend in the front knee.